Ester lubricants suitable for use in aqueous systems

ABSTRACT

Ester lubricants derived from high molecular weight dibasic acids, polyoxyalkylene glycols and monofunctional aliphatic alcohols are provided. These ester compositions are useful as lubricants and are readily emulsifiable with water. Aqueous emulsions of these esters have superior lubricating and rust inhibiting properties.

United States Patent Sturwold et al.

Oct. 14, 1975 ESTER LUBRICANTS SUITABLE FOR USE IN AQUEOUS SYSTEMSInventors: Robert J. Sturwold; Fred 0. Barrett, both of Cincinnati, OhioEmery Industries, Inc., Cincinnati, Ohio Filed: Nov. 15, 1974 Appl. No.2523,990

Related US. Application Data Division of Ser. No. 384,674, Aug. l, 1973,Pat. No. 3,857,865.

Assignee:

US. Cl. 252/495; 72/42; 252/56 S; 252/396 Int. CL". ClOM l/06; ClOM3/04; ClOM 5/04; ClOM 7/08 Field of Search 72/42; 252/495, 56 S,

[56] References Cited UNITED STATES PATENTS 3,857,865 l2/l974 Sturwoldet al 252/495 Primary ExaminerDelbert E. Gantz Assistant ExaminerI.Vaughn Attorney, Agent, or Firm-Gerald A. Baracka; John D. Rice ABSI'RACT 4 Claims, N0 Drawings ESTER LUBRICANTS SUITABLE FOR USE INAQUEOUS SYSTEMS This is a division, of application Ser. No. 384,674,filed Aug. 1, 1973 now US. Pat. No. 3,857,865.

BACKGROUND OF THE INVENTION The use of organic esters, primarilyaliphatic esters, as synthetic lubricants is well documented in theliterature. These compounds are useful in the neat form in a variety oflubrication applications. They are especially important for their use inengines because of their ability to perform acceptably over a widetemperature range. Complex synthetic ester lubricants obtained from thereaction of glycols and dibasic acids with monobasic acids and alcoholsare also widely used. These complex esters are generally characterizedby their excellent thermal stability, oxidation-corrosion resistance andlow temperature properties.

Recently the use of aqueous lubricant systems has become increasinglyimportant. In the metalworking industry, for example, because of thehigh cooling requirements of many of the high-speed operations employedfor the processing of metals straight mineral oil or vegetable andanimal oil lubricants are no longer completely satisfactory because theydo not have sufficient cooling capacity. This is particularly true inhot rolling operations. The trend has therefore been to the use ofaqueous lubricant systems to overcome the cooling problem as well asreduce sludging, discoloration and other related problems. Typically,aqueous emulsions containing from about 0.1 to 25% of an emulsifiableoil are employed for this purpose.

The conventional simple and complex synthetic ester lubricants haveheretofore not been adaptable for use in aqueous systems formetalworking even though they are in themselves highly efficientlubricants. They are incompatible with water and these oils do not formacceptable emulsions or dispersions without the use of highly efficientemulsifying aids.

It would be highly advantageous to have modified synthetic esterlubricants available which are readily emulsifiable with water anduseful for working both ferrous and non-ferrous metals. It would beparticularly useful if uniform aqueous emulsions could be formed withthese modified ester lubricants without the use of external emulsifyingaids by moderate agitation of the lubricant and water and if stable,i.e. did not undergo rapid phase separation, emulsions resulted. Itwould be even more desirable if the resulting aqueous lubricant systemshad superior rust inhibiting and lubricating properties.

SUMMARY OF THE INVENTION We have now discovered that ester compositionsderived from high molecular weight dibasic acids, monofunctionalalcohols and polyoxyalkylene glycols are excellent lubricants, both inthe neat form and when emulsified with water. These esters form stableemulsions with water which are useful for working both ferrous andnon-ferrous metals. In addition to the superior lubricating propertiesobtained with aqueous emulsions formed with the present esters, superiorrust inhibiting properties are also obtained.

The esters of this invention are reaction products comprising about 0.05to about 0.5 equivalent polyoxyalkylene glycol and 0.5 to 0.95equivalent monofunctional alcohol per equivalent dibasic acid. Excellentresults are obtained when the esters contain about 0.1 to 0.4 equivalentpolyoxyalkylene glycol, particularly polyoxyethylene glycols, and about0.6 to 0.9 equivalent monofunctional alcohol reacted with an equivalentdibasic acid. Additional hydroxylic or carboxylic reactants notexceeding about 0.4 equivalent can be included. The esters typicallyhave hydroxyl values and acid values less than about 25 and preferablythese values are less than 10. The polyoxyalkylene glycols used havemolecular weights from about 200 to 1000. The high molecular weightdibasic acids contain from about 32 to 52 carbon atoms with dimer acidscontaining predominantly C dibasic acids being preferred. Usefulmonofunctional alcohols will contain from about 1 to about 20 carbonatoms and preferably from about 6 to 16 carbon atoms. In preparing theaqueous emulsions the concentration of the ester in water will rangefrom 0,1 to about 25% by weight.

DETAILED DESCRIPTION The improved synthetic ester lubricants of thisinvention suitable for use in aqueous systems to impart supe riorlubricating and rust inhibiting properties are complex estercondensation products obtained by the reaction of a polyoxyalkyleneglycol, a high molecular weight dibasic acid and a monofunctionalalcohol. One or more additional other compounds capable of beingincorporated into the ester may be included in small amounts.

The polyoxyalkylene glycols employed have molecular weights from about200 to about 1000 with recurring alkylene groups containing 2 to 4carbon atoms. Polyoxyalkylene glycols satisfying the above requirementsinclude polyethylene glycol, polypropylene glycol, polybutylene glycol,poly(ethylenepropylene) glycol and the like. Especially useful for theester lubricants of this invention are polyethylene glycols havingmolecular weights from about 300 to about 800. The polyethylene glycolsare available from commercial suppliers under the trade designationsCarbowax and Polyox or they may be synthesized in the conventionalmanner. Molecular weights indicated for the polyoxyalkylene glycols areaverage molecular weights and it is understood that the compositions aremixtures of glycols ranging above and below the specified averagemolecular weight value. Polyoxyalkylene glycols having molecular weightsless than about 200 or greater than about 1000 should not, however, bepresent in significant amounts.

The high molecular weight dibasic acids condensed with thepolyoxyalkylene glycol will contain from about 30 to 60 carbon atoms.Especially useful dibasic acids are the so-called dimer acids containingfrom about 32 to 52 carbon atoms. The dibasic acids may be obtained byprocesses known to the art but, as with the dimer acids, they areusually obtained from the polymerization of monocarboxylic acidscontaining from about 16 to 26 carbon atoms. These unsaturated monomeracids may contain one or more sites of available unsaturation within themolecule. Dimer acids containing predominantly C dibasic acids andobtained from the dimerization of oleic acid, linoleic acid, elostearicacid and similar singly or doubly unsaturated C monobasic acids areparticularly useful for the preparation of the present lubricants. Toobtain the dimer acids 2moles of the unsaturated monocarboxylic acid arereacted, generally in the presence of a catalytic material such as analkaline, acid or neutral earth.

To remove ethylenic unsaturation the dimer acids may be hydrogenated.Mixtures of dimer acids derived from different sources may be employedand also trimer and tetramer acids may be present with the dimer acid.Trimer and tetramer acids are by-product acids obtained in thedimerization process and they do not adversely affect the properties ofthe resulting ester compositions so long as about 50% by weight of themixture are dimer acids. in some instances the presence of these trimerand tetramer acids may even be advantageous, such as when a higherviscosity for the ester is desirable. Excellent results are obtainedwhen the high molecular weight dibasic acid contains about 75% or more Cdimer acid. Commercially available compositions sold under the trademarkEmpol, which are mixtures of polymerized fatty acids having C dimer acidas the major constituent, may be advantageously employed to form theesters of this invention.

The monofunctional alcohols condensed with the polyoxyalkylene glycolsand high molecular weight dibasic acid contain'from l to about carbonatoms. These alcohols have the general formula ROH where R is ahydrocarbon radical containing from 1 to about 20 carbon atoms which canbe either straight-chain or branched, and if branched may contain one ormore alkyl groups containing from 1 to about 4 carbon atoms, and whichmay be saturated or contain unsatu ration. The use of mixed alcohols ofthe above types is not detrimental to this invention and in someinstances is even advantageous. Especially useful alcohols for thisinvention contain from 6 to 16 carbon atoms. Illustrative of thealcohols suitable for use in the present invention to obtain improvedester products include isopropanol, butanol, t-butanol, isoamyl alcohol,n-hexanol, Z-ethylhexanol, n-octanol, isooctanol, isodecanol, caprylalcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearylalcohol, tridecyl alcohol, which is mainly tetramethyl-l-nonanol, andhexadecyl alcohol which is a complex mixture of primary alcoholscharacterized as 2,2-dialkyl-l-ethanols where the alkyl groups aretypically methyl-branched C and C radicals. Branched alcohols containingfrom about 6 to 16 carbon atoms and which are saturated or essentiallyso are an especially preferred embodiment of the invention.

The alcohols may be obtained from any of the conventional processes. Forexample, long chain linear alcohols may be obtained from natural sourcesor produced synthetically from ethylene using Ziegler-type reactions.Tridecyl and hexadecyl alcohols, as well as other branched chainalcohols, are obtainable from the oxo reaction, that is, by the reactionof carbon monoxide and hydrogen with a suitable olefin.

in addition to the reactants described above, namely, the high molecularweight dibasic acids, polyoxyalkylene glycols and monofunctionalalcohols which are essential to obtain the improved esters of thisinvention useful as aqueous lubricants, small amounts of other reactantsmay also be included without detracting from the lubricant properties.in some instances, such additional modification may even impart enhancedphysical properties and characteristics to the esters, such as increasedviscosity, lubricity, oxidation and heat stability or the like. Forexample, small amounts of monobasic acids may be included in thepreparation of the esters. Similarly, short-chain glycols andshort-chain dibasic acids can be present. Such materials include, forexample, glycols such as ethylene glycol, 1,3-propanediol,1,5-pentanediol, l,6-hexanediol, 1,9-nonanediol, 1,10- decanediol,neopentyl glycol (2,2-dimethyll ,3- propanediol), adipic acid, sebacicacid, succinic acid, oxalic acid, glutaric acid, pimelic acid, subericacid, azelaic acid and the like. Aromatic and cycloaliphatic diols anddicarboxylic acids may also be used. Triand polyfunctional materialsincluding triols, tricarboxylic acids, polyols and polycarboxylic acidscan also be used. Hydroxylic and carboxylic compounds of this typeinclude glycerol, sorbitol, pentaerythritol, monohydroxypivalate,trimethylolpropane, the previously mentioned trimer and tetramer acids,trimesic acid, trimellitic acid and the like. Still other materialshaving mixed functionality, such as alkanolamines, can be employed.

These compounds can be included in the ester preparation in smallamounts to modify the physical properties of the esters. This aspect ofthe invention finds particular application where the resulting ester, inaddition to being used as a lubricant in an aqueous emulsion, may alsobe used as the neat oil, thus eliminating the need for the user to keepseveral different lubricant ester compositions on hand for thesedifferent applications.

The reaction of the dibasic acid, polyoxyalkylene glycol, monofunctionalalcohol and any other hydroxylic or carboxylic compounds which may bepresent is carried out using conventional esterification procedures,that is, by heating the reaction mixture with or without a catalyst at atemperature from about to 300C while removing the water of reaction.These condensation reactions are most generally conducted over thetemperature range to 250C. [t is not necessary that a catalyst beemployed for the reaction, however, conventional acid catalysts such assulfuric acid, alkyl and aryl sulfonic acid such as p-toluene sulfonicacid, or the like can be used to advantage. The reaction may be carriedout in a diluent which is inert to the reaction conditions employed andwhich preferably will form an azeotrope with water to facilitate itsremoval. The reaction is continued until the esterification is completeor essentially so. This may readily be determined by following thedecrease in acid value or hydroxyl value or by measuring the amount ofwater evolved.

The dibasic acid, polyoxyalkylene glycol and monofunctional alcohol maybe added to the reactor as a unit charge and the reaction conducteduntil the acid value indicates complete or near complete reaction of thecarboxyl groups or until a predetermined amount of water is recovered.When following this procedure the reactant charge should roughlycorrespond to the ratio of the reactants desired in the ester product.The reaction system should be essentially balanced but a slight excessof one or more of the reactants can be present. An alternativeprocedure, is to react the dibasic acid and the polyoxyalkylene glycoland when this reaction is complete, or essentially so, to charge themonofunctional alcohol and to complete the reaction. Still anothermethod for preparing the esters would be to react the dibasic acid andmonofunctional alcohol and when this esterification is complete to addthe polyoxyalkylene glycol and complete the reaction. In this latterinstance an excess of the monofunctional alcohol may be initiallyreacted, in fact, the dibasic acid may be completely reacted withmonofunctional alcohol so that no free carboxyl groups remain. Thepolyoxyalkylene glycol may be added and a transesterification reactionundertaken to displace the appropriate amount of monofunctional alcohol.The higher boiling polyoxyalkylene glycols readily displace themonofunctional alcohols using suitable transesterification conditionsand the resulting products are comparable in all respects to thoseobtained using conventional unit charge or step-wise esterificationprocedures. The common esterification and transesterification catalystscan be used.

An alternative but less desirable procedure for the preparation of theester lubricants of this invention would be to react the dimer andmonofunctional alcohol in the presence of ethylene oxide, in otherwords, the polyoxyalkylene glycol would be prepared in situ. Suitablecatalysts and/or diluents could be added. For maximum control of thereaction and of the products obtained it is preferred that thepolyoxyalkylene glycol be prepared prior to reaction with themonofunctional alcohol and high molecular weight dibasic acid.

It is evident that considerable variation is possible in the preparationof the esters of this invention, however, to obtain acceptableemulsifiability and lubrication it is necessary to maintain a balancebetween the high molecular weight dibasic acid and polyoxyalkyleneglycol. The esters should contain at least about 2% by weight reactedpolyoxyalkylene in order to obtain acceptable emulsification with water,however, the amount of polyoxyalkylene glycol reacted should not exceedabout 40% by weight since above this level the lubrication propertiesand the rust properties begin to decrease. For best results the estersshould contain about 5 to about 30 weight percent reactedpolyoxyalkylene glycol.

The esters of this invention have acid values and hydroxyl values lessthan 25 and preferably the acid values and hydroxyl values are less than10. It is evident, therefore, that while the ester compositions need notbe balanced with regard to stoichiometry best results are observed whena balanced or essentially balanced ester is obtained. The reactantcharge can be varied, of course, depending on the particular method usedto prepare the ester as discussed above. In general, however, thepolyoxyalkylene glycol will range from about 0.05 to about 0.5equivalent per equivalent of high molecular weight dibasic acid and,more preferably, will range from about 0.1 to 0.4. The monofunctionalalcohol will range from about 0.5 to 0.95 equivalent per equivalentdibasic acid, however, best results are obtained with 0.6 to 0.9equivalent monofunctional alcohol per equivalent dibasic acid. If otherhydroxylic reactants are included in the ester preparation the amount ofpolyoxyalkylene glycol and/or monofunctional alcohol will be reducedaccordingly. If a second carboxylic compound is included in the reactionthe amount of dibasic acid will be reduced accordingly. In general theamount of additional reactants, either hydroxylic or carboxylic, willnot exceed 0.4 equivalent and preferably will be less than about 0.25equivalent.

The ester lubricants of the instant invention find particular utility inmetalworking operations where a high degree of cooling by the lubircantis required. The esters are preferably used as aqueous emulsions wherethe concentration of the ester in water ranges from about 0.1 to about25 percent by weight and, more preferably, from about I to about byweight. The resulting aqueous lubricant formulations may be added to themetalworking elements, such as the working rolls, or may be applied tothe metal itself by spraying or immersion of the metal sheet in asuitable bath. These esters applied in the form of aqueous emulsionsform a uniform continuous lubricant film between the working rolls andthe metal to provide efficient lubrication. In addition they have a highdegree of cooling capacity. The lubricant emulsions are useful for theworking of both ferrous and nonferrous metals. They may be formulatedwith other additives such as stabilizers, corrosion inhibitors and thelike. The lubricant emulsions may be conveniently recycled for reusewith the result that considerable economic advantage can be realized.Makeup water may be required to bring the ester to the originalconcentration. It may also be desirable upon recycling to strain orfilter the residue in order to remove metal scale or other particlespicked up during the processing operation. This is particularly truewhere the aqueous lubricant emulsions are applied by the use of spraynozzles.

The present esters are readily emulsifiable with water in theproportions indicated above and do not require the use of additionalexternal emulsifying aids to obtain a stable emulsion. The emulsions arereadily formed using simple agitation and, once formed, the emulsions donot undergo rapid phase separation but remain emulsified for longperiods. In certain instances where extremely stable emulsions aredesired, it may be advantageous to add a small amount of one or moreother external emulsifying aids commonly employed for this purpose,however, this is not necessary to get a good emulsion.

In addition to use in the emulsified state, the present esters can alsobe used in the neat form, that is, the straight oil can be utilized as alubricant. The modification of these esters with polyoxyalkylene glycoldoes not significantly impair the lubricating effectiveness of theesters. When used in the neat form the oil may be blended with othersynthetic ester lubricants, mineral oils or the like and combined withadditives to achieve the desired formulation.

The following examples directed to the preparation of the estersdescribed above and their utilization as lubricants illustrate theinvention more fully, however, the examples are not intended to limitthe scope of the invention. All parts and percentages in the examplesare given on a weight basis unless otherwise indicated.

EXAMPLE i To a glass reactor equipped with a stirrer, thermometer andwater trap fitted to a condenser were charged 212.8 gms hexadecylalcohol (a commercially available complex mixture of primary alcoholscharacterized as 2,2-dialkyl-l-ethanols where the alkyl groups aretypically methylbranched), 35.2 gms polyoxyethylene glycol having anaverage molecular weight of about 400 and 252 gms dimer acid (acommercially available polymerized acid sold under the name Empol l0l8and consisting of about 83% C dibasic acid and 17% C tribasic acid). Aslight excess of the hexadecyl alcohol was employed based on thecalculated equivalents charge ratio of 0.8:0.2:l.0 (hexadecylalcoholzpolyoxyethylene glycol:dimer). the reaction mixture was heatedat 220C under a nitrogen atmosphere for about 12 hours until the acidvalue had decreased to about 3.8 and 15.7 mls water were taken off. Acidvalues are determined in accordance with A.O.C.S. Test Method Tela-64-T. The mixture was then heated to about 250C under vacuum forabout 1 hour to strip off the excess hexadecyl alcohol. 42.5 Gramshexadecyl alcohol were removed. The resulting lubricant ester had anacid value of 3.1 and hydroxyl value of 5.6.

A portion (20 mls) of the ester was poured into 100 mls of cold tapwater while stirring with a glass rod. The ester immediately emulsified.This emulsion was stable and showed no signs of phase separation afterstanding 24 hours at room temperature. Even after 72 hours the emulsionwas not completely broken and was readily reformed with minimalagitation.

A 1% aqueous emulsion was prepared and used to determine the rustresistance of the aqueous lubricants. The test is conducted by placing afilter paper into a petri dish and lightly sprinkling cast iron filingsover the paper. The aqueous emulsion is then poured over the filings towet the paper and cover about one-half the filings. The dish is covered,allowed to stand undisturbed and the amount of discoloration (rustformation) observed at 15 minute intervals. If after 2 hours there is nodiscoloration or only a trace of discoloring the aqueous emulsion isconsidered to have good resistance to rust formation. The rustresistance of the 1% aqueous emulsion prepared with the above ester wasrated good even under these severe test conditions.

To demonstrate the effectiveness of esters of this invention aslubricants, both as aqueous emulsions and in the neat form. they wereevaluated using a Falex machine. This machine provides a convenient andreliable means of determining the film strength or load-carryingcapacity of lubricants as extreme pressures are applied. Falex testingis recognized throughout the industry as a means of measuring therelative effectiveness of various lubricants. The Falex wear test (ASTMD 2670-67) utilized 60 gm sample of the ester lubricant of 5% aqueousemulsion thereof. The loading device is attached and the cup containingthe sample positioned so that the steel pin and blocks are completelyimmersed in the test sample. The load is then increased to 350 poundsand run for 5 minutes. After this time the load is further increased to1000 pounds and maintained for 30 minutes. The difference between thereadings taken at the beginning and end of the 30 minutes indicates theamount of wear. Each unit represents 0.0000556 inches of wear. The lowerthe wear number the better the material is considered as a lubricant.When dealing with 5% aqueous emulsions, wear values less than 25 areconsidered good and numbers less than are rated excellent. A 5% aqueousemulsion of the above ester gave only 9 units of wear which isexcellent.

To further demonstrate the ability of these aqueous emulsions tofunction as lubricants under extreme pressures, additional testing wasconducted with the Falex machine. After satisfactory completion of thetesting at 1000 pounds for 30 minutes the load is increased by 250pounds and run for one minute at the increased load. If the metal pindoes not fail this procedure is continued until failure. Upon failure,the last load reading prior to the failure is reported. The aqueouslubricant prepared with the present ester satisfactorily withstood aloading of 2750 pounds before failure.

EXAMPLE ll Employing equipment and chemicals similar to that describedin Example 1, except that isooctyl alcohol was substituted for hexadecylalcohol a lubricant ester was prepared. 351 Grams dimer acid and 49 gmspolyoxyethylene glycol were first reacted with stirring between about200C and 210C for about 2% hours until the acid value was 136 and 3.5mls water was collected. The reaction mixture was then cooled and 159.7gms isooctyl alcohol charged. The reactor and its contents were thenheated at about 220C for about 7 /2 hours. After this time the acidvalue of the reaction mixture was 5.2. A vacuum was applied to thesystem for about 1 hour to remove unreacted isooctyl alcohol. Theresulting ester product, which based on the amount of unreacted isooctylalcohol recovered, contained 0.2 equivalent of PEG 400 and 0.8equivalent isooctyl alcohol reacted per equivalent of dimer acid, had anacid value of 5.2 and a hydroxyl value of 9t2. The ester had aflashpoint of 595F and firepoint of 640F as determined using ASTM testprocedure D 92-66. Viscosity (ASTM D 445-65) at F and 210F were 181 and21.4 centistokes, respectively. The ester formed stable emulsions veryreadily without the aid of external emulsifying aids. A 1% aqueousemulsion of the ester tested in accordance with the rust test previouslydescribed showed good resistance to rust formation. The Falex test on a5% emulsion showed 25 and reached 2250 pounds before failure.Significant improvement of the performance properties of these aqueousemulsions is possible by the addition of suitableadditives such as EPagents, antifoam agents, bacteriostats, etc. and the emulsions give goodresponse to the addition of these materials.

EXAMPLE Ill To demonstrate the versatility of the present invention alubricant ester was prepared by reacting 1 equivalent dimer acid, 0.2equivalent polyoxyethylene glycol, 0.3 equivalent neopentyl glycol and0.5 equivalent Z-ethylhexanol. The reactants were added as a unitcharge, heated initially at 180C and then at 220C until the neartheoretical amount of water was evolved. A vacuum was pulled on thesystem for /2 hour at 220C to remove the slight excess of 2-ethylhexanolwhich was present and unreacted. The reaction mixture was cooled andfiltered after the addition of a diatomacious earth filtering aid. Theester product had an acid value of 5.5, a flashpoint of 615F andfirepoint of 655F. The viscosities of the ester at 100F and 210F were376 and 37.4, respectively. The ester emulsified readily and a 5%emulsion showed only 8 units wear in the Falex test. This is even moresurprising considering that the undiluted ester gave 1 16 units wear inthe same test.

EXAMPLE 1V Following the procedure described in Example 11, except thatthe monobasic alcohol was butanol, an ester was prepared utilizing 1equivalent dimer acid, 0.2 equivalent PEG 400 and 0.8 equivalentbutanol. The final ester product had an acid value of 6.2, a hydroxylvalue of 5.3, with flashand firepoints of 580F and 640F, respectively.Stable emulsions were obtained with the ester and a 1% aqueous emulsionwas rated good in the rust test. Falex wear with a 5% aqueous emulsiongave only 20 units wear.

EXAMPLE V Using a similar procedure and the reactants described inExample 1V, except that the polyoxyethylene EXAMPLES VI AND VIIEmploying a preparative technique similar to that described in ExamplesII, esters having the following equivalents ratios were prepared:

EXAMPLES VI VII Dimer Acid l.0 eq. 10 eq. PEG 400 0.1 eq. 0.4 eq.2-Ethylhexanol 0.9 eq. 0.6 eq.

Ester VI was reacted to an acid value of 2.3 while the lubricant esterVII had an acid value of 4.3. Both esters were readily emulsifiable withwater with moderate agitation and the emulsions were homogeneous and didnot undergo rapid phase separation. One percent aqueous emulsions ofboth of these esters had good ratings in the rust test. A aqueousemulsion of the ester of Example VI showd 25 units of wear in the Falextest while the emulsion prepared with the ester of Example VII gave 22units of wear.

The superior and unexpected results obtained with the synthetic estersof the present invention are evident from the following demonstrationwherein an ester was similarly prepared except that the PEG 400 was notincluded in the reaction. The ester was the reaction product of 1equivalent dimer acid with 1 equivalent 2- ethylhexanol and had an acidvalue of 2.5 and a hydroxyl value of 0.7. This ester was notemulsifiable with either hot or cold water even with vigorous agitation.To obtain an emulsion with this ester required the use of 20 wt. of anexternal emulsifying aid (lgepal 630-a commercially availableethoxylated nonyl phenol) and even then the emulsion was not stable. Anemulsion containing 5% of this ester gave 140 units of wear in the Falextest. Also these emulsions had poor rust prevention properties.

EXAMPLES VIII X Esters having an equivalent ratio of I.0:O.2:0.8 (dimeracid: PEG 400:monobasic alcohol) were prepared. Various commerciallyavailable mixed straightchain alcohols manufactured by the oxo processwere used in these examples. For ester VIII a mixture of C and Calcohols was used while for preparation IX mixed C and C alcohols wereemployed. A mixture of linear alcohols containing 16 to 20 carbon atomswas used in Example X. The table below sets forth the acid value andhydroxyl value obtained for the resulting esters and the resultsobtained in the Falex wear test and rust test with emulsions preparedwith these esters:

The emulsions obtained with the above esters were all homogeneous andhad good stability.

EXAMPLE XI An ester comprising the reaction product of 1 equivalent Cdibasic acid, 0.2 equivalent polyoxyethylene glycol having an averagemolecular weight of 400 and 0.8 equivalent tridecyl alcohol, consistingmainly of tetramethyI-l-nonanols, was prepared using a procedure similarto that described in Example II. The resulting lubricant ester wasreadily emulsifiable in water in all proportions and the emulsions soprepared had excellent stability and showed good rust resistance whenplaced in contact with cast iron filings. A 5% aqueous emulsion of theester gave only 1 1 units wear after 30 minutes testing at 1000 poundsand withstood 3250 pounds pressure before failure.

EXAMPLE XII To further demonstrate the advantage of the presentinvention an ester was prepared by reacting l equivalent of the dimeracid with 2 equivalents polyoxyethylene glycol (400 average molecularweight) at 200C to 220C until the acid value reached 5.05. There wereinsoluble materials present when it was attempted to emulsify this esterwith cold water. The ester could be emulsified in hot water but afteronly one-half hour the emulsion was essentially completely separated. Anemulsion containing 5% by weight of the ester gave 139 units of wear inthe Falex test.

We claim:

1. An aqueous lubricant composition suitable for metalworking and havingimproved rust protection properties containing about 0.1 to about 25percent by weight of an ester comprising the condensation product of0.05 to about 0.5 equivalent polyoxyalkylene glycol having a molecularweight from about 200 to about 1000 and having repeating alkylene unitscontaining from 2 to 4 carbon atoms, 0.5 to 0.95 equivalentmonofuntional aliphatic alcohol of the formula ROI-l where R is analiphatic hydrocarbon radical containing from 1 to about 20 carbon atomsand 1.0 equivalent of a dibasic acid containing from about 30 to 60carbon atoms, said ester having an acid value less than 25, a hydroxylvalue less than 25 and containing about 2 to about 40 percent by weightpolyoxyalkylene glycol.

2. The aqueous lubricant composition of claim 1 wherein thepolyoxyalkylene glycol is a polyethylene glycol having a molecularweight from about 300 to about 800, the monofunctional alcohol containsfrom about 6 to 16 carbon atoms and the dibasic acid is a dimer acidcontaining from about 32 to 52 carbon atoms.

3. The aqueous lubricant composition of claim 2 wherein 0.1 to 0.4equivalent polyethylene glycol and 0.6 to 0.9 equivalent monofunctionalalcohol are reacted per equivalent dimer acid, the ester contains fromabout 5 to about 30 weight percent polyethylene glycol and has an acidvalue less than 10 and a hydroxyl value less than 10.

4. The aqueous lubricant composition of claim 3 containing from about 1to about 10 weight percent of an ester derived from a dibasic acidcontaining or more C dimer acid, a polyethylene glycol having amolecular weight of about 400 and 2-ethylhexanol.

Disclaimer 3,912,642.R0be7"t J. Stmvold and Fred 0. Baw'ett, Cincinnati,Ohio. ESTER LUBRICANTS SUITABLE FOR USE IN AQUEOUS SYS- TEMS. Patentdated Oct. 14, 197 5. Disclaimer filed Nov. 3, 1975, by the assignee,Emewy Industries, Inc. Hereby enters this disclaimer to claims 1, 2, 3and 4 of said patent.

[Ofiicz'al Gazette J (mum/y 13, 1976.]

Disclaimer 3,912,642.-R07)e1"t J. Stmuold and Fwed 0. B await,Cincinnati, Ohio. ESTER LUBRICANTS SUITABLE FOR USE IN AQUEOUS SYS-TEMS. Patent dated Oct. M, 1975. Disclaimer filed Nov. 3, 197 5, by

the assignee, Emem I nclustm'es, Inc. Hereby enters this disclaimer toclaims 1, 2, 3 and 4 of said patent.

[Oyficz'al Gazette Jamm rg 13, 1.976.]

1. AN AQUEOUS LUBRICANT COMPOSITION SUITABLE FOR METALWORKING AND HAVINGIMPROVED RUST PROTECTION PROPERTIES CONTAINING ABOUT 0.1 TO ABOUT 25PERCENT BY WEIGHT OF AN ESTER COMPRISING THE CONDENSATION PRODUCT OF0.05 TO ABOUT 0.5 EQUIVALENT POLYOXYALKYLENE GLYCOL HAVING A MOLECULARWEIGHT FROM ABOUT 200 TO ABOUT 1000 AND HAVING REPEATING ALKYLENE UNITSCONTAINING FROM 2 TO 4 CARBON ATOMS, 0.5 TO 0.95 EQUIVALENTMONOFUNCTIONAL ALIPHALIC ALCOHOL OF THE FORMULA ROH WHERE R IS ANALIPHATIC HYDROCARBON RADICAL CONTAINING FROM 1 TO ABOUT 20 CARBON ATOMSAND 1.0 EQUIVALENT OF A DIBASIC ACID CONTAINING FROM ABOUT 30 TO 60CARBON ATOMS, SAID ESTER HAVING AN ACID VALUE LESS THAN 25, A HYDROXYLVALUE LESS THAN 25 AND CONTAINING ABOUT 2 TO ABOUT 40 PERCENT BY WEIGHTPOLYOXYALKYLENE GYCOL.
 2. The aqueous lubricant composition of claim 1wherein the polyoxyalkylene glycol is a polyethylene glycol having amolecular weight from about 300 to about 800, the monofunctional alcoholcontains from about 6 to 16 carbon atoms and the dibasic acid is a dimeracid containing from about 32 to 52 carbon atoms.
 3. The aqueouslubricant composition of claim 2 wherein 0.1 to 0.4 equivalentpolyethylene glycol and 0.6 to 0.9 equivalent monofunctional alcohol arereacted per equivalent dimer acid, the ester contains from about 5 toabout 30 weight percent polyethylene glycol and has an acid value lessthan 10 and a hydroxyl value less than
 10. 4. The aqueous lubricantcomposition of claim 3 containing from about 1 to about 10 weightpercEnt of an ester derived from a dibasic acid containing 75% or moreC36 dimer acid, a polyethylene glycol having a molecular weight of about400 and 2-ethylhexanol.